Temperature compensated tangent



Jan. 22, 1957 DQUGLAS 2,778,224

TEMPERATURE COMPENSATED TANGENT Filed June 27, 1955 INVENTOR.

WKW

United States Patent 2,778,224 TEMPERATURE COMPENSATED TAN GEN T Robert Ritson Douglas,

Meter Company, tion of Delaware Erie, Pa., assignor to American Incorporated, Erie, Pa., a corpora- In gas meters, changes in temperature affect the gas volumeand the stiffness of the diaphragms, both of which affect the registration. This invention is intended to compensate for the temperature efiects by a thermostatically adjusted tangent which changes the length of the tangent art to offset the temperature eifects. By reason of the compensation, the meter registration is corrected to correspond to gas at standard temperature so the meter registration corresponds to the heat units.

- In the accompanying drawing, Fig. l is a top plan view of a typical tangent, Fig. 2 is an end view of the tangent, Fig. 3 is a top plan view of the Fig. 1 tangent equipped with temperature compensating elements, Fig. 4 is a bottom plan view of Fig. 3, Fig. 5 is a section on line 55 of Fig. 3, Fig. 6 is a diagram illustrating the operation, and Fig. 7 is a section on line 77 of Fig. 4.

Figs. 1 and 2 show a typical tangent having a tangent arm 1 with an opening 2 for receiving a crankshaft to which the tangent arm is rigidly connected, for example, by soldering. The tangent arm has a flattened body with screw threaded edges 3. The flattened body of the tangent arm extends through a slot 4 in a cross-head 5 so that the cross-head can be moved along the tangent arm and clamped in adjusted position between nuts 6 and 7. Adjusting screws the cross-head move the cross-head transversely with respect to the tangent arm and thereby adjust the angular relationship of a wrist pin with respect to the tangent arm. The wrist pin 10 is rigid with the cross-head 5. The construction so far described is or may be of common construction. The length of the tangent arm is adjusted by the nuts 6 and 7. The timing is adjusted by the screws 8 and 9. Most tangents include both. the length and timing adjustments although any particular tangent may have a substantially different appearance.

With the tangent shown in Figs. 1 and 2, the meter will register correctly for gas at standard temperature, for example, 60 F. At higher and lower ambient temperatures, the cubic feet registration of the meter will not correctly indicate the heat units of the metered gas because of the eifect of the temperature upon the gas and upon the diaphragms of the meter. In order to provide the temperature compensation, there is fixed on the wrist pin 10 a bushing. 11 having at its upper end a tubular projection 12 which is connected by solder 13 to the wrist pin. The solder 13 also connects the tubular projections 12 to a bracket 14. Beneath the bracket 14 is a washer 15 which rests on a shoulder 16 on the bushing. Below the Washer 15 is a crank arm 17 which rests on a shoulder 18. While the bushing 11 and plate 14 are rigidly fixed to the wrist pin 10, the crank arm 17 is freely pivoted on the bushing which serves as a pivot for the crank arm 17 and, accordingly, the crank arm 17 can freely pivot relative to the wrist pin 10.

As shown more clearly in Figs. 4 and 7, the crank arm 17 is pivoted by means of a riveted connection 18 to one end of a link 19. At the other end, the link 19 has fixed thereto a wrist pin 20 which slides in a guide way or 8 and 9 threaded in opposite ends of slot 21 in the bracket 14 extending along a center line connecting the crankshaft and the wrist pin 10. The rivet 18 has a spool-shaped head 21a with end flanges 22 and 23 embracing upper and lower surfaces of an arcuate portion 24 on the plate 14. The arcuate portion 24 is centered on the wrist pin 10 and the flanges 22 and 23 provide a support for the crank arm 17 and link 19. The plate 14 has a stop 25 which engages the rivet 18 and limits the movement of the crank arm 17 in a counterclockwise direction as viewed in Fig. 3 (clockwise as viewed in Fig. 4). When the stop 25 comes into play, the rivet 18, the wrist pin 10, and the wrist pin 20 are substantially on the same center line. This is the low temperature position of the tangent. In this position,

the wrist pin 20 is closest to the crankshaft and the measuring stroke of the gas meter diaphragm is shortest. Accordingly, each stroke of the diaphragm measures a smaller quantity of gas which is appropriate when the gas is at a very low temperature and has its maximum density.

The temperature control of the position of the wrist pin 20 is effected by a coil-shaped thermostat 26 having one end 27 rigidly fixed to a flange 28 on the crank arm 17 and having its other end anchored to a member 30 slidable in a slit 31 in the plate 14.: The purpose of the slidable member 30 and the slot 31 is to fix the end 32 of the thermostat 26 in a fixed angular relation'with respect to the wrist pin 10 but to permitradial movement in the slot so that the thermostat will not have restraints. In other words, the thermostat 26 is free to assume its normal position.

Under the expansion and contraction resulting from changes in temperature, the end 27 of the thermostat 26 pivots the crank arm 17 about the wrist pin 10 as a center. This causes a gradually increasing movement of the wrist pin 20 in the slot 21 as the crank arm 17 turns clockwise about the wrist pin 10 as viewed in Fig. 3. This action is more clearly evident from Fig. 6 which is a greatly simplified drawing. The motion of the wrist pin 20 can very accurately compensate for the temperature effects in the meter so that the meter registration will accurately reflect the heat units in the gas instead of the cubic feet.

This temperature compensating construction can be applied to any tangent. It will be noted from Fig. 3 that the angular adjustment screws 8 and 9 are readily accessible from the top and that clearance openings 33 and 34 in the plate 14 provide access to the stroke or length adjustment nuts 6 and 7. Accordingly, all of the usual adjustments for gas meters tangents can be made on a standard tangent. 'The parts for etfecting the temperature compensation, namely, the bushing 11, the support 14, the crank arm static element 26 comprise a separate assembly which can be mounted on the wrist pin of any conventional tangent. When so mounted, the wrist pin 20 of the thermostatically controlled assembly becomes the wrist pin of the tangent and yet the movement of the thermostatically controlled wrist pin 20 does not affect the construction and calibrating adjustments of the conventional tangent such as that disclosed in Figs. 1 and 2. Accordingly, the calibrating adjustments can be made on the conventional tangent and the elements providing the temperature compensation then provide the additional temperature compensation without interfering with the calibrating adjustments.

Although the wrist pin 20 is thermostatically moved, the reciprocating forces incident to the operation of the meter cause substantially no changes in the position of the tangent. The reciprocatory forces are transmitted from the wrist pin 20 through the link 19 and are largely taken by the crank arm 17 rather than by the thermostat 26.

Patented Jan. 22, 1957' 17, the link 19 and the thermo- I The wrist .pin.20, accordingly, is not substantially moved y the. rec pr ato tyi tces incident. to, the .crzeraticate the meter. Furthermore, increasing valve friction makes a meter displace more gas volume than recorded and increases the-torquezon the. wrist-pin. 2t ina direction which partially compensates the greater displacement.

What is. claimed as new is: r

.1. In a gas meter tangent, a tangent ,arm fort-connectiontto a crankshaft, a pivot: on. thetangentnarm spaced from the. crankshaft, means on thectangent armfior adjusting the pivot with respect tozthextangent arm toward and away from the crankshaft, abracket fixed to the pivot, said bracket having a guide way therein extending along a center line connectinguthe crankshaft. and pivot, a crank arm-pivoted on the pivot, a wrist pin slidable in the guide way, .a link connectingithe-crank arm and-wrist pin, and a thermostatic element responsive to gas. temperature connected between the bracket and crank-arm for pivoting-the crank arm in: accordanceswiththegas temperature.

2.-In a gas meter tangent having-a tangent .arm for connection to a crankshafntanrwrist pin on the tangent arm and spaced from the crankshaft, and means. on the tangent arm for adjusting the relative distance between the wrist pin and crankshaft, the combination of-temperature compensating mechanism having a bracket fixed to the wrist pimsaid brackethaving a-guide way therein extending alongta center line. connecting; the;crankshaft and wristpin, a crank; arm. pivoted; on the wrist -pin,.-.a second wrist pin for connection to the meter measuring mechanism slidable in the guidetway a connecting the crank arm and the second wrist: pin, and a .thermo static element responsive .totgas temperatureconnected between the bracket and crank arm for pivoting the crank arm in accordance with the gas temperature.

3 in a gas meter tangent having a tangent armrfor connection to a crankshaft, a :wrist pin. on. the tangent arm and spaced from the crankshaft, and means, onuthe tangent arrn for adjustablymoving. the Wristpinmward and away from the crankshaft, dthetcombination ofy-a bushing fixed to the wrist pin, a bracketfixedto thebushing, said bracket having a guide wayttherein gextending along a center line connecting thewcrankshaftand wrist pin, a crank arm pivoted on the bushing, a; second wrist pin slidable in the. guide way, adink: connecting; the crank arm andzthe second wrist pin, and; a, thermostatic element responsive to gas temperature connected'between the bracket and, crank arm for pivoting theycrank arm in accordance with the gas temperature.

4. Ina gas meter tangent, abracket: folsrwnnecti flx a crankshaft, a wrist pin =movably 'mqllmfi 91 2 sai bracket, a crank arm having one end pivoted on the bracket, a link connected between the other end of the crank arm and the wrist pin, and a thermostat responsive to gas temperature mounted on the bracket and connected to the crank arm for turning the crank arm, said bracket having a guide way for the wrist pin extending along a center line connecting the crankshaft and wrist pm.

5. In ac asmeter tangent, a support for connection to a crankshaft, a wrist pin movably mounted on said support, a linkage comprising a crank arm and link connected to each other by a common pivot, the crank arm having an end extending from the common pivot and pivoted on; the support, the link extending from the common pivot and having an end connected to the Wrist pin, a thermostat responsive to gas temperature mounted on the support and connected to the linkage for turning the crank arm, said support having guide means for the wrist pin: extending along. acenter line connectingithe crankshaftland Wrist .pin.

1 6. :In ages meter tangent, a support for. connection, to, a.

crankshatt, awrist pinmovably mounted on the support, acranktarmyhaving one end pivoted'on the support, a link connected between the other end, of the. crank arm and=wristpin, v-means for adjustably moving the end of thecrankgarm pivoted; on the support; toward andaway from the crankshaft, a thermostat responsive to; gasternperatnrerandfiounectedbetween the crank arm and supportfon tnrningwthe-crankarm, n aidr ppo t h vingra guide wayxtorz-the Wrist rpinext n ng. lo g a c nt r line conne ting the rankshaft and wrist pin.

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RefereucasCited in-the file of this patent l UNITED STATES PATENTS 2339956 *sine s Jan; 25,1944 

